Computer based control of such systems has long been known, and has reached a considerable level of sophistication, as exemplified by U.S. Pat. No. 5,086,385 (Launey et al). A concern with such systems is to provide a capability for exercising a range of monitoring and control functions through peripheral units of widely differing types, as well as providing for future expansion of the system to allow for additional peripherals, possibly of types not contemplated when the system was originally designed. Any attempt to provide a wholly comprehensive control program to provide for all anticipated eventualities will result in a complex program and system which is difficult to program and maintain. Even then, new types of peripherals will still require reprogramming, while if the program is simplified to provide only for installed peripherals, expansion of the system will always require a revised control program.